oak trees defoliated by caterpillars

Help! My Oak Trees are Dying!

Does it look like your oak trees are dying? Throughout the year, various caterpillars occur on oak trees, munching on the leaves. Large infestations of caterpillars can devastate your trees, appearing like they are dead.

In the spring, I can always count on the tussock moth crawling on every surface around me from the trees. The tent caterpillars will build their ugly webs in the crotches of the trees. In the summer and fall, oakleaf caterpillars, bagworms, and webworms rear their ugly heads.

Sometimes the caterpillars are quite noticeable because you see them everywhere. Some have stinging hairs like the tussock moth in the spring or puss caterpillar in the summer that can really irritate the skin.

tussock moth

Tussock moths crawl down from trees to make cocoons. Photo by Donald Hall, UF.

Once when I walked inside, I had a tussock moth hanging on my collar! It was cute and fuzzy, but I was racing outside to flick it off so the stinging hairs wouldn’t touch my skin.

I also know when it is caterpillar season when I get reports of caterpillar poop raining down on buildings, sidewalks, and pools.

Do they cause Sudden Oak Death Disease?

Other times, homeowners report that their oak trees have died almost overnight. They often suspect that it is Sudden Oak Death, an emerging disease that is not yet found in Florida.

variable oakleaf caterpillar

The variable oakleaf caterpillar has been the culprit of massive infestations this summer. Photograph by Ellen Light.

Suspecting this disease, homeowners will alert the Florida Department of Agricultural and Consumer Sciences (FDACS). We have confirmed that these “dying” trees are not infected with a pathogen, but are actually the victims of munching caterpillars. In this case, it was the variable oakleaf caterpillar.

Although there are many other reasons that CAN cause an oak tree to die.

This rainy summer season was the perfect environment for hungry caterpillars.  In turn, they have defoliated quite a few oak trees in the area. They work fast! The homeowner often doesn’t notice until the trees are looking pretty naked especially if the tree isn’t right over the house.

Don’t fret if your tree is one of these victims. Most trees can grow their leaves back if they are healthy.

For more information, Dr. John Foltz with the UF Entomology and Nematology Department has a devoted page to Forest and Shade Tree Insects.

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